Check valve



dan. 14, 1936.

CHECK VALVE M. sElBT 2,027,455

Filed Jan. 21, 1935 c Fig. 2.

I l A flellljlllrlll /VHX 5.5/67 BY Parenteel Jan. 14, 193s PATENT OFFICE 2,027,455 CHECK` VALVE Max Seibt, Dresden, Germany Application January 21, 1.933, Serial No. 652,877

Germany January 25, 1932 4 claims. (cl. 251-124) This invention relates to a check valve for pipings, especially in connection with centrifugal pumps.

It has already been proposed to employ dash 5 pots in check valves for pipings to eliminate the rattle due to the opening and closing ofthe valves at fluctuations of pressure. It has further been proposed to overcome the slowness of motion of the valve due to the use of such means by connecting the cylinder with the pressure piping so as to have the piston act as a power piston.

According to the invention, these power pistons are used lfor a different purpose, namely, for opening or closing the check valve slowly like a pneumatic door closer in order to avoid in the pipings the muchfeared knocks caused by sudden opening and closing of the valve; the power piston is also used as a substitute for expensive remote control of the valve,- orv for a motordriven device enabling the valve to open and close slowly.

'I'he invention' attains its objects by exposing the piston on the side of the cylinder and the rod to different piping pressures before and behind the valve, so that the diierences in pressure will produce counter forces which have a braking effect during the opening and closing of the check valve. nected with the check valve in such a Way that in overcoming a small openingV or closing angle the path -of the piston will be larger than while passing through the remaining angle. The braking eiect can be increased'during the opening and closing of the valve by providing the piston on the cylinderA side with a closing or opening mandrel for the end of the connecting piping opening into the cylinder. To regulate the opening and closing speed of the valve a. passage regulating device may be built into the connect- 40 ing piping.

By way of example, one form of the invention is illustrated in the accompanying drawing, in which Figure 1 is a longitudinal section ofv a check valve fitting and Fig. 2, a cross section thereof on the line A-A, of Fig. 1. l

In' the casing a the flap e is disposed by means of the lever f so as to be rotatable about the shaft d. If turned correspondingly, the Bap e will cover the seat surface c and close the opening slot guide g which engages a bolt n attached to a divided piston rod-mwhich is connected with a piston i, the bolt n being surrounded by a sleeve 1 o and being guided within a slide p formed in l ap on the annular face c on the other.

For this purposethe piston can be conthe carrying arms b of the cylinder h. By means of these arms b the cylinder is heldon one side on the pivot d and on the other side on thel fitting a. vThe outside of the cylinder h and the. piston rod side of the piston i are subjected to- 5 to pressure prevailing behind the nap e'. The piston i provided with rings 1c and movable within the cylinder h, has on the cylinder side a pointed mandrel l capable of fully entering the end of a' pipe r opening into the cy1mder body. The 10 pipe r is passed by means of a'stufng box g through the wall of the itting a and can be closed by a regulating device having the form of an adjusting screw u for varying the .sectional passage of the piping s. The rst partv of the pipe lies 15 in front of thecheck valve or of the opening to bevclosed thereby, and is formed by a baille member t. In the piping a three-way-coek `'u is provided for draining the contents of the cylinder and testing the tightness` of the piston i2() on the one hand and testing the tightness of the On the end of the pivot d passing through a stuiling box 1b a signal device :c is disposed, as shown in Fig. 2. The signal device :n comprises a lever :vr rotat- 25 able along with the shaft d and adapted to establish an electrical connection with a plurality of electrical contacts 3:2 which are connected to a source of electrical energy not shown in the drawing. y 30 In case of several check valves all of them may be interconnected by rods and act jointly on the braking piston.

The cylinder with the piston can of course be disposed outside the .casing a., 35 A The check valve arrangement according to the lAccording tothe invention, delivery begins, however, gradually, and for the following reasons:

When the flap is closed, thepistonz is in a posi.- 45

tion in which its mandrel l completely closes thev opening of the pipe r. If the ap e begins to open, it tends to draw the piston i outof the cylinder h whereby a vacuum is produced by the piston .i on th'ecylinder side thereof, since the pis- 50 ton or it's rod m has to travel the large braking path C-B compared with the small opening angle a I and the contents of the piping, usually water, cannot follow quickly enough through the connecting pipe s or the regulating device u. This ef- 55 tect is initially increased owing tothe fact that the mandrel l closes the pipe r almost completely, then less and less during further opening and releases it entirely only aiter the opening angle a i has been attained. However. since behind the ilap e, i. e., on the piston rod side, great pressure prevails, the piston has a braking eilect on the opening, and to these diierent pressures the counter pressures are due. i

When the opening angle a I has been attained, further opening up to the large angle a 2 can take place more quickly, and only the small braking path B-A is negotiated by the piston.

When the opening angle increases, the weight of the ilap will make itselil felt more and more as closing force so that a throttling etl'ect could be produced thereby, which, however, isprevented by the development of overpressure in the member t infront of the ap e and thus in the cylinder h during the increased velocity of iiosv, while behind the ilap e and on the rod side of the piston a vacuum is produced owing to the losses in now.

This diil'erence between the two pressures represents a force which continually works against the closing force of the weight of the ilap whichv is thus kept up and cannot have a throttling eifect.

During opening, a braking force is rst acting on the opening iiap e through the connecting pipes and-by the piston; and this tractive force is'converted during increasing pressure in the piping and piston into a pressure force which .opens the ilap more rapidly and keeps it open.

In case of the closing motion o! the valve the pressure force wor against the weight of the flap e changes into the opposite, for the reason that there prevails now overpressure on thegpiston rod side and vacuum on the cylinder side due to reversal of ilow. The traction force resulting hereirom together with the weight of the ilap causes rapid negotiation of the braking path A-v-B and thus rapid closing oi' the ilap about the closing angle a 2, while the small closingangle a I requires again the larger braking path B -C How-V ever, as simultaneously the pressure against the flap e and the pressure diiierence between 'pressure on the piston rod'side and the vacuum on the member t or on the cylinder side increase, further closing of the ilap goes mn rapidly also until, in spite of increasing closing forces, energetic braking takes placel at the beginning oi' the closing angles l' duetothefactthatthemandrellofthe piston closes the pipe r more Vand more and thus produces high loverpressureinthe braking cylinder as a counter force. This closing process corresponds to normal operating conditions requiring quick closing and slowopening.

I claim: i. A check valve, particularly for cenwhen sam sap is adjacent to as `tritugalpumps,acasinglutvingan inlet and an outlet, a cylinder connected with said casing. a movable piston within said cylinder, an oscillatable flap adapted to closesaid inlet, means operatively connecting said ilap with said piston, a pipe having one end connected to said casing adjacent to said inlet and another end leading into the interior of said cylinder, and a mandrel carried by said piston and adapted. to close the second-mentioned end of said pipe.,

2. A check valve, particularly for driving centriiugal pumps, comprising a casing having an inlet and an outlet, a cylinder connected with said casing, a movablepiston within saidvcylinder, an oscillatable flap adapted to close said inlet, means operatively connecting said nap with said piston, a pipe having one -end connected to said casing adjacent to said inlet and another endA leading into the interior of said cylinder, a mandrel carried by said piston and adapted to close the second-mentioned end oi said pipe and a regulating device connected with said pipe.

3. .A check valve, particularly for driving centrifugal pumps, comprising va casing having an inlet and an outlet, a cylinder connected with said casing, a lmovable piston within said cylinder, tan oscillatable ilap adapted to closesaid inlet, means operatively connecting said ap with said piston, a pipe having one end connected to said casing adjacent to said inlet and another end leading into the interior oi said cylinder. a mandrel carried by said piston-and adapted to close the second-mentioned end of said pipe, a` regulating device connected with said pipe, a baille member on the iirst-mentioned end of said pipe, and a three-way-cock carried by said pipev between its first-mentioned end and said regulating device.

4. A checl: valve, particularly iorcentriiugal pumps, comprising a hollow casing having an inlet and an outlet, a cylinder connected with said 4 casing, a movable piston within said cylinder, a nap situated within said casing between the inlet and the outlet, a lever having one end-portion connected with said ilap and another end-por.

tion having' the shape oi' a'curved slotted guide, A,

said lever oscillating said' iiap between a closing position, in which said flap closes said inlet, and

' an open position, a pivot carried by said casing and oscillatably supporting said lever intermediste its two end-portions, a bolt said slotted guide, a piston rod connected with said piston and carrying said bolt, and means connecting the inlet of said casing with one end of the cylinder, the travel of the pistongbeing comparatively 'greater when said flap is adjacent to itsv closingposition and being comparatively smaller openposition. 

